Shock-absorbing mechanism



' 3 1927. May A. P. WITHALL SHOCK ABSORBING MECHANISM Filed No 14, 1925s Sheets-Sheet 1 Inverubr p fllberfF/Ydfidl 192 May 3 A. P. WITHALLSHOCK ABSORBING MECHANISM 6 Sheets-Sheet 2 Filed Nov. 14, 1925 74422625: Int/Mr f 9 fllberZFWM 441/. c 172/ May 3, 1927.

6' I 1 K C:

V r j0/7///// 7 1,627,367 A. P. W lTHALL SHOCK ABSOHBING MECHANISM FiledNov. 14, 1925 6 Shuts-Sheet 3 Wdneas 4ZW%7W By 09 6 1 627367 M 1927 A.P. WITHALL snocx ABSORBING MECHANISM Filed Nov. 14. 1925 s Sheets-Shebt4 A. P. WITHALL Snocx ABSORBING MECHANISM May 3 Filed Nov. 14, 1925 6Sheets-Sheet 5 Patented May 3, 1927.

UNITED. STATES PATENT OFFICE.

ALBE BT I. WITHALL, OF CHICAGO, ILLINOIS, ASSIGNOR TO W. H. MINER, INC01' CHICAGO, ILLINOIS, A CORPORATION OF DELAWARE.

snocx-azasor'mme MECHANISM.

Application filed November 14, 1925. Serial lfl'o. 68,987.

This invention relates to improvements in shock absorbing mechanisms,and, more particularly, shock absorbing mechanisms for railway draftriggings.

While my present improvements are adaptable for use with both freightand passenger equipment, they have been articularly designed for use onthe locomotives and cars of modern passenger trains operated atrelatively high speed and wherein alarge number ofpassenger cars areused per train,

and for this reason. the description herein after following will bedirected more particularly to the problem of passenger train service. iTo obtain a certain peculiar conditions which have encountered in modernpassenger train ser vice, it is advisable to outline in abrief way thedevelopments which have taken place in draft gears and thecharacteristics of draft gears having the best available action prior tom imfention as known to me. As is well known to those skilled in theart, the first type of draft-gear was that of'a single spring. Thesingle spring type of gear was adequate for a short time until the 'sizeof cars and size of locomotives increased to the I point where woodsub-structures for supporting the draft gears were insutlicient andchange was made to the steel underframe construction. Greater shockabsorbing capacity in the draft gear was then demanded and was met byintroducing two springs in gears of the type. known as the twin springand tandem spring gears. These. gears, which provided a free springaction throughout the entire compression stroke proved adequate for manyyears, until ultimately,

thegradual increase in size of individual cars, increase in number ofcars per train, and increase in tractive etfort of the locomotivesbecame such that still greater ultimate shock absorbing capacity wasrequired, the maximum available shock absorbing capacity of a tandem ortwin spring gear having been limited to about 50.000 pounds.

The next change. in the development, of the art to meet the newconditions was the intr duction of the friction gear which combined anumber of friction elements with a spring resistance so as to produce ashock absorbing device having a much thorough undelstand'in of brakescould be applied more. rapidly and thereb bring a train to a'stop morequitlliy.

and in a shorter distance, permitting sp ier operation of trains. Thisfactor. produced greater disturbances in thedraft gears and producedconditions. that were not satisfactorily met by the friction em,developed up to this time. One new. problem was that requiring easierstarting of passenger trams without excessive shock or vibration beingtransmitted to the cars,' causing discomfort to the passengers. Thefriction gear was relativelytoo stifi in action and presented too greata frictional capacity in the lower range of the compression stroke.Initially, this problem was solved by the introduction of a preliminaryspring action in the form of a preliminary spring independent of otherspring means infconjunction with the friction elements, ;Temporarily.this type of preliminary spring gear met the requirements of service,but again, as still further increased demands arose, it was found thatthis type of prelimina'ry spring action friction gear was inade uate forthe reason that the independent pre iminary spring provided for only arelatively short stroke of limited capacity and the preliminary springwas constantly being utilized to its maximum capacity with conse quentmaximumfiber stressesin the spring and resulting short life, in thepreliminary spring. This condition resulted from the fact that thetractive effort of the locomotive under normal running conditions wassuch as to maintain the preliminary spring under its full permittedcompression, and necessitating thefriction part of the gear being inaction even-under normal running conditions. I

The next and final advance prior to my improvements, speaking broadly,to obviate the high fiberstresses of the springs within the preliminaryspring action range was to 55 tive as above outlined.

utilize the main springs of the fri tion gear as preliminary springsfora short part of the stroke.

It has been found, however, with the press- 6 cut day requirements inpassenger service, with still longer trains and higher-powered passengerlocomotives, that there are two distinct problems that have not beenheretofore solved so as to eliminate the discoml fort of the passengers.As is. well known,

in standard passenger practice, the maxiniuiii traetive etl'ortof'modern passenger locomotives, it being understood that the maximumti'active etforl, of a locomotive is the tractive effort produced theinstantv before the power applied to the drivers becomes so great as toovercome the adhesion between the rails and drivers, causing thedriversto slip. under normal rail conditions, starting 2-9 at zero, isapproximately within a range of 40.000 to 00,000 pounds draw-bar pull,and

the sustained traetive etl'ort, under spced,

varies approximately from 30,000 to about 50,000'poui'ids. 1n starting'atrain. therefore. such locomotives exhaust or use up all of the free orlive spring action of any such gems as liavelieretofore been availablehaving a preliminary free spring action and consequently the gears areactuated to a pointsomewhere within the friction range of such gears. Asthe locomotive.acquires speed, the sustained traetive effort is such asto exceed the available free spring capacity of such prior gears, and,consequently, the

gears between the locomotive and the cars rearwardly of thelfltftllfltltlVO remain partially eoinpiessed somewhere in the frietionrange of the eoii'ipressio i stroke. it. is further well known thatlocomotives, partieularly of certain types most commonly eniployedon thewestern railroads having long hauls over heavy grades, develop a verydelinitcly perreivable pulsation. Coiiseipienttv, where the sustainedtraetive effort is such as to keep the gears of the locomotive andforward cars of the train always partially I con'ipressed and within thefriction range, there is no available free-spring action of such geaislO'CllSlliOll or compensate for the. )ulsat'ions which are transmittedbackturb'ing to passengers and particularly is this true of those carsof the train immediatelv at the. rear of the locomotive. I

Notwithstanding the advances that have been made as indicated in thepreceding paragraphs, there has still remained a very seriousdisadvantage in the operation of, passenger trains. 'l'his disadvantage,resi-iltt lg oftentimes in extreme discomfort to passcn-' gers undercritical conditions of operation, is caused by continued pulsationsimparted wane passenger cars, the pulsations being distinguished fromthe usual shocks such as encountered when starting .or stopping a train.In other words, the practically cont nuous pulsations occurring asfrequently as 180 per minute, particularly emphasized under certaincritical running conditions, are present when the train is running undera substantially constant speed, or when acuilerating after havingstarted.

The cause of these pulsations is undoubtedly due to the lack of balanceof the counter-weights and moving parts of the locomotive at certainspeeds, that is, there may he one speed at which the locomotive will runwith the parts reasonably balanced, but any variation 'ttllOVQ or belowsuch critical speed produces the unbalanced effect that, in turn, eansesthe pulsation eti'ectjn the movements of the locoliiotive. Obviously,passenger loeomolives have such -a wide range of speedthat,the"pulsation in effect from the lack o'f'b'alance in such a wide.range beexniies extremely noticeable at different times and, unless suchpulsations can be prevented from being transmitted to the ear or carsrearwardly of the locomotive, the etl'cet on the passengers is extremelyannoyiiig and discoinforting to the passengers.

While the source of thedillicult-y referred to has been known for sometime. the. efforts :heretofore made to overcome. the pulsation.ell'eetiii the operation of passenger trains,

have proved unsuccessful. (lertain types lot relatively stitl'. actionfriction gears on passenger cars have performance eharaeterist es as torender them praclieally uiil siiitabli iii any degree for this type of'l r'ei\'iee., Some other types of friction gears :have bel -n found morcellicient in that they i are more sensitive in the setting up of tliefrietioiaction, and particularly in release. the off at has, therefore,been directed heretofore llil'u-t'tltally entirely towardproducinggrcater and greater sensitiveiiess in the flielioil gear partsso as to obtain a quicker release in the hope that the pulsations fromthe locomotive would be accommodated by an instantaneous setting andii'istant-aneons release of the friction parts. The greatest advancesalong these lines, so far as known to me, have been attained in thosetypes of friction gears employing anti-friction devices between thewedge setting parts of the friction elements. Howeverftlie adyanees madealong these lines have proved inadequate and all insutlicieiit toeliminate pulsation effect, there being certain linii tations from'amechanical standpoint preventing the-making of the friction parts loolei;-

sensitive beyond a certain point. As will be appreciated,the wedge orgripping action must be set up instantaneously and, in reducing thefriction between the wedging parts by anti-friction means, there is agradual concentration of the pressure or stresses on very minute areasof contact which, if the imposed on a device of this character,eliminate transmission -'of the extremely rapid pulsations from alocomotive rearwardly to cars in hack thereof, since pulsations occurwith such rapidity when the train is under speed as to prevent thealternate instantaneous setting 'up andinstantaneous release of thefriction grip between friction alemcnts that would be necessary with theresult that the friction mechanism remains practically set under certainconditions even though the gear may not be under a full compressionstroke, or even a'major portion of a compression stroke.

My discovery, stated broadly, is that a free, live and constantlyavailable straightspring action of sutlicient capacityto equal or exceedthe sustaincd-tractive effort of a locomotive under given conditionsmust always be available in order that the pulsation etfect be preventedfrom transmission tov the cars rearwardly of the locomotive. In otherwords, regardless of the per cent of total compression of the gear, andregard- }css of whether or not the friction unit, as

such, may be set or in an active gripping condition, there must beavailable, sufficient free spring capacity operable independent of anyrelease of the friction unit, as such, to compensate for an variationsin the way of pulsations or 0 range in draw-. our pull, no matter howrapidly alter-' derstood that 60,000 pounds is approximately the maximumdrawbar pull a modern passenger locomotive is capable'of exerting.

,In carrying out my discovery, therefore, I have found that it isnecessary to provide an always available free spring capacity which willat least equal or preferably exceed the-sustained tractive et'i'ort ofthe locomotive under given conditions in order that. the pulsations fromthe locomotive may be anti rely prevented from being transmitted back tothe cars in the rear of the locomotive.

other prob cm that has been presented in modern passenger servicethat-arises from the practice of certain railroads which re-' quires theen ineer, in stopping a train,- to apply the bra 'es only on the carsrearwaidly of the locomotive, and not to the driving wheels, to therebysave the tires of the looo motive drivers from excessive wear. .In thismethod of operation, the locomotives, which are heavy, tend to run 1aheadfreeof the cars, and consequently, there is a. stretching out orcompression of the draft gears ofseveral of the cars of the tramrearwardly' of the locomotive to such an extent as to compress the gearsof those cars to points within the friction range of the compressionstrokes thereof and the train is brought to"- -the cars of the train,until the gears have been released out of the friction range andrestored to their normal or neutral condition before the locomotive canbe. started in a forward motion to accelerate'the train; By providing analways available free spring capacity, nail to or in exccss of-the ;su$.tained tractivc effort of the'locomoti-ve, and preferably at least equaltothe maxiniun'r tractive effort of the locomotive, this backing up ofthe locomotive to start a train is rendered unnecessary with myimprovements. i v q The condition of modern passenger train servicereferred to in theimmediately preceding paragraphs are such as occur inthe normal operation of the-trains. However, as is well known, abnormalconditionsof shock are bound to occur, due, for instance, to emergencyapplication of the brakes which requires a shock absorbing capacity inthe gears far in excess of anythatis available in a straight springgear. In the switching of cars, a cushioning capacity is necessary totake care of excessive shocks,

and, furthermore even in the starting of a long train the momentumacquired by the locomotive and cars immediately rearwardly thereof willbe such that, before the last car or cars of the train are picked u .andac; celerated, the pull imposed upon the rear or rear cars will exceedany available capacity of a free spring gear that could be mounted inthe limited space, and ,with the limited stroke allowed in ractice. Theavailable space, as known to t lose skilled in the art, is definitelyprescribed as to width. height and length, and also the permissiblelength of the compression stroke is limited. In the carrying out of myinvention, the same has been done with dueregard to practicallimilncidentl my improvements solve nil-1 tations of space andcompression stroke, and furthernune, with full consideration for thenecessity of eliminating any abrupt change in the shock absorbingcapacity of the mechanism, pm'ti ularly in the change from the freespring action to the friction action,

in other words, proper provision has been made for a smooth and easytransition from the free or live spring action into the friction actionof the gear.

One object of my invention, therefore, is to provide a shockabsorbingmechanism con forming to modern limitations of available spaceand .stroke, particularly adapted for passenger train equipment; whereinthere is provided, "1 effect, a free spring gear per-- mitting easystarting of a train and always available. for absorbing any normalshocks aml pulsations that may occur. in the opera tion of the. train,and combined therewith, a friction mechanism as an emergency shockabsorbing device available to absorb execs: sive or abnormal shocks,with all the advantages of a high capacity free spring gear and 'all theadvantages of a high capacity friction gear, and elimination of thedisadvantages aml limitations of both types.

More specifically, an object of my invention is to provide in a combinedspring and friction shock absorbing mechanism, an mstantaneouslyavailable free. spring action at any point in a compression stroke ofthe mechanism which will equal or exceed any sustained tractive effortof a passenger locomotive under speed.

Still another object of my invention is to n-ovide in a shock absorbingmechanism iaving the free. spring capacity of the.character outlined inthe preceding paragraph,

'a reserve friction shock absorbing mechaursm ol lngh capaclty. of suchcharacter that clcarly appear from the dcs ription hereinafterfollowing, considered in connection with the drawings aml the subjectmatter of the appended claims.

In the drawings forming a part. of this specification, Figure l is ahorizontal. longitndinal, sectional view of a portion of a railway draftrlgglng, showing my unprovements inconnection tlurrewath, Illustrating'the mechanism in full release, the section through the frictionelements and shell c0rresponding to two sectional planes 120 apart.Figure 2 is a longitudinal, vertical, sectional view of the shockabsorbing mechanism shown in Figure 1, the section through the frictionshell and friction elements corresponding to two section planes 120apart. Figure 3 is a view similar to Figure 1, illustrating the positionof the elements of the shock absorbing mechanism with the main springcompressed to the' extent of its free action and the compensating springcone pressed to a predetermined linnted extent. Figured" is a viewsimilar to Figure2, showing the gear compressed to the same extent asillustrated in Figure 3. Figure 5 is a view similar to Figure 3 showingthe gear fully compressed. Figure 6 is a view similar to Figure 3illustrating an instantaneous cUJltlitiOtl of the parts of the mechanismim mediately after a heavy shock has been ab sorbed aml the load' hasbeen decreased. Figure 7 is a front end, elcvational view of the shockabsorbing mechanism proper. Figure 8 is a transverse vertical,sectionalview corresponding substantially to the line 8---8 f Figure 1.'Figure 9 is a transverse vertical sectional view corresponding,substantiallyto the line 9-9 of Figure 1. Fig ures It) and 11 aredetailed, perspective views respectively, of the friction shell and themain spring follower. Figures 12 and 13 are detailed, perspective views,respectively, of the wedge member and a friction shoe. 95 Figure H showsan indicator diagram of the action of a typical passenger type shockabsorbing nu-chanism with best performance cliaractcristits known to meprior to my invention. Figure [5 shows an indicator diagram illustratingthe action of the improved shockabsorbing mechanism herein shown anddescribed. 7 And Figure 16 is a combination of the two indicatordiagrams of l ignres 14 and l! for the purpose of (3011b 105 parlson.

in said drawings, 10-40 indicate channelshaped center or draft sills ofa railway car underfralue, to the inner surfaces of which are securedfront. stop lugs 11-'-11 and rear stop lugs 1212. "The inner end of thedrawl-ar is indicated at 13. to which is operatively connected a hoodedyoke 14 of wellknown form. Although I have herein illustratcd a hoodedyoke, it will be evidentthat a yoke having swireled connection with thedrawbar such as is commonly employed in passenger equipment or any otherwell known form of Yoke and drawbar may be employed. The shock absorbingmechanism proper. as well as a main follower 15, is disposed within theyoke. The yoke and the parts thercwithin are supported in operativeposition by a detachable saddle plate 16.

The specific embodiment of a friction shock absorbing.mechanism, which Ihave chosen to illustrate my invention, comprises, broadly, thefollowing broadly termed elements or par-ts, the specific details andchart mit thelateral insertion of the main spr n .wall 17 adapted tocoqperatewith'the rear stop lugs 12 in the manner of the usual follower.The opposite sides of the casing are left open .as indicatedat 18-18 toresistance element C; At the forward en of the casing the side walls areflanged inwardly as indicated at 19l9, thereby'pro- 'ders 20 present stosults hereinafter set forth.

riding vertically disposed inner shoulders 2020. The top and bottomwalls -at the forward end of the casing are cut away as most clearlyshown in Figures 2 and 3, there by providingahntment faces 21 ada ted tocooperate with the inner end of the riction shell B to act as limitingstops. The shoulwhich limit the outward movement 0 the friction shell ashereinafter more specifically pointed out.

The friction shell B is in the form of a substantially cylindrical.casting' having opposed, laterally projecting fianges22 at the rear endthereof, the flanges being adapted to cooperate with the shoulders 20to-limit the outward movement of the friction shell with reference tothe casing A. The arrangeinent is such that the shell is insertible in avvertical direction between the shoulders 20 and the abutment faces 21of the casing A, and the spacing of the shoulders 20 and the abutment21008 21 ofthe casing A, is designed so as tov permit a predeterminedmotion between the shell and easing of the extent and to attain thefunctions and re- The interior of the shell B is provided with a seriesof-independent, true cylindrical friction surfaces 23 23, the same beingconverged, inwardl of the shell. At the'forwardside of ea ii flange 22,is provided a horizontally dis.

posed recess 24 adapted to cooperate with a. rib 25 in theeorrespondingfian e 19 of the casing A to pr e rent lateral disp acementof the shell B witl i're fercnce to the casing and hold thepaitsia'gsenibled when 'the mechanism is in; the, full released positionillustrated inel igure l.

The thrccfi'iction shoe; D, E and are of similar design, except ashereinafter pointed outi; Each shoe is formed with an outertruccylindrical friction surface 123 adapted to cooperate with thecorresponding shell frictionsurface 23 and aninner, inclined face 26 ofrelatively lar e contact area. fornicd on the front side 0 a lateralenlargement 27 on the shoe. The faces 26 of the two shoes D and E extendat a relatively blunt and readily releasable angle with respect to thelongitudinal axis of the mechanism and the face 26 of the shoe E extendsat a relatively keen true wedging angle to said axis. The rearfaces ofthe enlargements 27 of the shoes bear on a spring follower" 28 in theform of a disk.

The spring follower 28 in'turn bears on the forward end of thecompensatin s' r' J.

The wedge G, as shown, is in t he foi h i of a cast block suitabl cored,having a flat front face-29 adapter? to hear directly on the frontfollower 15. At 'the inner end, the block G is provided withthree,rearwardly convergingfaces 126" 126,ieach of relatively large area,arranged around the axis of the mechanism. Two of the' faces 12600-1161; with :the faces 26 of the twoblunt angle shoes D and E and are;correspondingly mclined thereto, whereas-the-jremaining triie wedge face126 of theblock'istinclined to correspond with the'wedg'e', face 26 of'the shoe F and adapted to cooperate therewith.

rounding the boss'aud's aced' therefrom so as to rovide a pocket afaptedto 'a-ccommo date I: 1e rear end-of the compensatin springresistaiice J. The followerH -"is a so" provided with four,spaced-,forwardly. QPOJQCIF ingdugs 32732 at the front-sidethereof, the lugs 32being arranged inqpairs at o .posite sides of the. ;follower. The fronten 3 0f the in engage the inner end of the frietion sheli durmgcompressioq of l the .mechanism. The flat-front side-6f:-the'annularflange 31. isadapted'tO co-Gperateat certain times, withthe-inner ends-of the-friction shoes D, E arid 'F. The central; boss 30is .recessed as indicated at .33- to f'feceive the head of the retainer,bolt and is slotted as indicatedat 34 to. accommodate-the shank of thebolt. clearlyshown in-yFigui-es 1 and 11, the'recess 33 isopeniatz-oneside to permit lateral insertion of the bolt head.

-Th e;0uter end of the bolt:K- is anchored to the wedge block G, the nutof the bolt being accommodated within a recess in the block.

. 'Jlhe retainer bolt adapted tofinai-ntain Jthe mechanism of uniformoverall length and ,l10ld the spring J under an initial compression ashereinafter deseribed. .The lugs 32 serve to retain the friction shellB'against lateral displacement. the shell being-provided with a pair ofprojections 35.35 at the inner .end thereof adapted toen 'a'ge betweenthe correspondingspairs of ugs32.

As shown in Figures 1 and 2, the inner ends of the friction shoes D, Eand F are nor- I 5 length;

mally spaced from the front face of the annular flange 31 of the springfollower ll.

The twin arranged main spring resistaneo elements C are interpmedbetween the spring follower H and the'transvcrse end wall I? of thespring cage Each member of the twin arranged. springs comprises an,iuner, relatively light coil and an outer heavier coil.

After many extended experiments, I have found that a very ellieicnt gearcapable of accomplishing the resultshereinlael'ore set forth in astructure having the elements :u'- ranged as hereinbefore described, isohtained by employing main springs having a total ultimate capacity ofapproxitately 540,000 to 85,000 pounds and hy'allowitig for apredetermined limited relative movement l|etween' the friction shoes andshell and a movement of the friet ion shell with respeet t0 the springcage of approximately inches, or one-half of the total :U'ulltll'lh'compression stroke. \Vith this arrangement and capacity of the parts-1,the avail hle free spring capacity at the time tlav-"frietiou s tell isstopped in its |novement relative to the cage, is approximately 55,000to 00,000 pounds, and while I am am} I.; tl attluf -.-distance andcapacity figures-abovegiven may mechanism is adjusted to Also, I providefor-a transition period in excess of that heretofore employed so far asknown and preferably there is left aclearspring; J is a comparativelylight capacity spring so designed that it may be compressed of an inchbeyond the normal initial cone pression under which it IS placed whenthe gear is assembled without developing (:xccs

'stve liher stresses, said spring functioning to automatically adjustthe friction shoes and wedges compensating for wear on thesurfam-s andpermitting proper adjustment of the parts iu'olitaining' the overalllength of the mechanism. In addition, it will be ohvious that saidspring J also functions, in (ftIllJtltttflltllt with the friction shoesand frict on shell proper as thespring of a friction mechanism for alimited time during the transition period in building up the resistancein the change from the straight spring action to the final full frictionaction of the mechanism. With the foregoing described constructi n andcapacities and predetermined relative movement of the 'parts in mind,the

operation of my improved mechanisnn as- -that 'llu! friction unit,comprising the friction shell and friction elements therewithin, ,n:oves bodily without anyappteciahle friction aetlon. This preliminaryfree spring .aet ion is permitted forIl inches so that there. will hedcvelopedat the-end ofsaid period of action, a resilient capacity, ofappr'oximately 55,000 to('|0,000;pounds capactty. rin Figure 15,-thecompression line, start- ||g at a, representing an initial compresn, onof 10,000 pounds, follows the line ad.

Iiy referenceto the diagram shown In; his connection, it will beunderstood 'Tnthe diagrams of Figures :14 and seen as'jlfi, thehonizontal lines repre- 'n pounds andij'the vertical lines vetitent ininches; The next accomprcssio'n Stroke, if .thfe shock rhed' is-i greatenough, is the transinthe'tru'elfree spring action to the action, this.being represented in the-"f diiigram on the. pressure curve from d "to:-f,.' 'wherein it will be noted that there is a smooth upwardly risingcurve developing at the end of the inches of transition, a capacity ofapproximately 90,000 to 95.000 pounds. In this con'ncction,'.the the.free'spring action of the mechanism is represented by the shaded area0, cl, e and the transition period by the differently shaded area d, f,g, e. 'The indicator diagram denotes a definite line of separation ofthe 'free spring action and the transition act-ion. hut in actualpractice. there will probahly he some slight overlapping of thetransition action into the late part of the frcespring action. dependingupon the initial frictional resistance to relative movement between theshoes and the shell and correspondingly, there has been 11 the degree ofinitial compression in the compensating spring J, but for practicalpurposes, the action is substantially as indicated in the diagram ofFigure 15. In this figure, the line b, c, a represents the releaseaction. In Figure 14, the release action is represented by the line b,c, a",

Before proceeding further with the description of a compression stroke,it will be observed that there has beenbuilt up during the free springaction. a relatively high resistance, up .roximatelybz'iQQO- to 60,000pounds, as a oresaid, and that this resistance is increased at amorerapid rate but without abrupt change,'until apprdximatel true riction ofthe mechanism for the lastinches of the'compre'ssion stroke occurs. Inother. words, prior to theinitiation of the true friction action of themechanism,

there is already developed, a very high resistance and consequently, thecorresponding load on the friction elements is high in starting the truefriction action. It is in this connection that the particular type offriction unit which I have provided, is important in that, by the use ofthe blunt .and keen faces between the wedge and the shoes, I am enabledto employ a relatively acute, true wedgin angle on the set of faces 26and 126 of the shoe F and wedge without danger of the parts stickingwhen released, since the blunt sets offaces 26 and 126 of the shoes Dand E and the wedge always assure release. Furthermore, as hereinbeforepointed out, large areas of contact are provided between the faces ofthe wedge and the faces of the friction shoes so that, althoughextremely heavy loads are applied to these parts and required to beabsorbed quickly duringa remaining comparatively short portion of thecompression stroke, there will be no such concentration of pressure onany element. as to upset any of the metal or imbedding of onepart withinanother. During the last Z4 inches of movement in the c mpressionstroke, the action will be. a true friction action and the compressioncurve will follow the line approximately indicated by f-b in Figure 15with an ultimate total capacity of the mechanism of approximately300,000 pounds.

(Under a full compression, the parts will assume the position shown inFi re 5.)

Re erring now to Figure 6 of the drawing, wherein an instantaneouscondition of the mechanism is illustrated as occurs immediately afterthe absorption of a heavy shock. In this figure, it will be observedthat the shell B is moved outwardly a part of its possible travel butthere has been thus far practically no relative movement be tween thefriction shoes and the shell. 0 partial 90,000 to 95,000 pounds beforetheexpansion of the main spring resistance unit, thereby providing acertain amount of free spring capacity prior to release of the frictionelements. When the conditions are such that the applied force dropsbelow that illustrated by the condition of the parts in Figure -6,theshell will continueto move outwardly until movement thereof islimited, whereupon the shoes will be forced outwardly with'reference tothe shell, the degree of relative movement between the shoes and theshell depending uponthe amount of reduction of applied pressure. After aheavy blow has been absorbed, compressing the gear as illustrated forinstance in Figure 5, and thereafter the load has dropped to a pointbelow the maximum tractive effort of the locomotive, but with asustained trac tive effort still being imposed upon the mechanism, as:when the train is running under speed, the conditions assumed by theparts will range within the limits of the condition illustrated inFigure 6 and'a condition where outward movement of-the shell has beenarrested and the friction shoes 'and wedge and associatedcompensatingsprin'g J have moved outwardly a slight distance withrespect to the friction shell B. It will he noted that under thecondition illustrated in Figure 6, even though pulsations are beingimparted to the locomotive, there is still available the free springcapacity of the main spring resistance unit to absorb or cushion suchpulsations or-oscillation's, not- -withstanding the fact thatthefriction unit proper has not completely released and is in a compressedcondition. Furthermore still referring to Figure 6, shouldthe train vbebrought to a stop with the shock absorbing mechanism in condition asshown in Figure 6, there is available a free spring action which willreadily permit the en- .gineer to start the train without the necessityof backing up.

By employing blunt and keen faces on the wedge and shoes, they may be sorelated as to permit an easy blending or transition from the ultimate,high free spring capacity to thettrue friction action. \Vith suchfriction .clements, regardless of the keenness of the wedgi'ng anglewhich may be required, the area of contract will always be sufficientlygreat as to prevent concentrateddestructive stresses in either the wedgeor th'e shoes.

Referring now to the indicator diagrams in Figure 14 and 16. The diagramin Figure 14, corresponds to that of the best commercial spring frictiongear "heretofore available for passenger service, so far as known to me.In this type of mechanism, the initial compression is comparatively lowand normally is under 5,000 pounds. The free spring action is availablefor only a half inch and consequently, the maximum free spring capacityavailable, represented by the line a (l' is not; in excess of 20,000

v of

pounds. The transition period represented by the line d'f, in the bestknown practice heretofore, approximates an eighth of an inch, with a'resulting maximum capacity at the end of the transition period ofapproximately only 25,000 pounds. The true friction action isrepresented by the line /"-I/. \Vith such a mechanism, it is obviousthat a locomotive exerting a sustained tractive effort of say 40,000 to45,000 pounds, necessarily is imposing on the mechanism such a load asto compel the mechanism to pass into and remain within the true frictionaction range. Consequently, pulsations from the. locomotive aretransn'littet'l to a stiff. rigid, non-yielding mechanism, since thefriction parts never have opportunity to release; the freesp'ringcapacity is always. exhausted; and the pulsations are insufficient toproduce actuation of the. friction unit as such. differences in theaction of the two mechanisms is best shown by the sluu-rimposedindicator diagrams of Figure lti, whcrethe available free sprmg capacityof myunprovedmechanism is shown not only to far exceed that of the otherprior known mechanism, but shows-clearly the availability of the freespring action always within the. sustained tractive effort of the.locomotive and with the reserve friction action in cases emergency forabsorbing abnormal shocks.

Observations lave-shown that, in actual practice, over 95,5 of theshocks encountered in normal operations of passenger trains will fallunder the maximum-tractive effort of the. locomotive. \Vith myiunwovenu-nts, these are all absorbed by the free spring action whichpromote the life of the mechanism from two distinct angles. The first.of these is due. to the fact that such large percentage ofshocks aretaken solely by the. main springs in the lower r m'es of ti r stres rsof the springs, that is, without compressing the springs up to theirmaximum permitted fiber stresses. This prevents fatigue of the springsand consequently 'prolongs the life thereof. The second factor is due tothe fact that the friction unit proper is called upon for scrvice only avery small percentage of the time and consequently there is eliminatedthe rapid coustant back and forth movements of the shoes relative to theshell. which, even though they may be comparatively minute to absorbcomparatively small shocks. are destructive of the friction surfaces andcause unnecessary rapid wear thereof. llence. the life of the frictionunit is materially prolonged.

l have herein illu tratcd one spccilic cml'milllll'tnl of my invention.and described with particularity certain features. capacitie andclmracteristics thereof. I am aware that various changes andmodifications may be made, both in structure and .in spring capacities,relative permitted movements of the partsat'ld otherwise, witboutdeparting from the spirit of the invention. All such changes amlmodifications are contemplated as come within the scope of the claimsappended hereto.

lclaim:

f, In a shock absorbing mechanism, adapted for railway draft riggings,subject to a known sustained maximum drawbar pull from a locomotive,said mechanism comprising: a spring resistance unit; a friction unitcomprised of a pluralit' of elements relatively movable when saidfriction unit. as such, is operated, said friction unit being bodily andinactively movable relative to'the spring resistance unit for apredetermined initizrl portion of the compression stroke of themechanism, and thereafter the parts of said friction unit relativelymovable to create friction resistance, the

a vailable free spring capacity of said spring resistance unit whilesaid friction unit as such is inactive, being in excess of said knownsustained lnaximlim draw-bar pull to thereby freely cushion all normalshocks and pulsations within the range of the said sustained maximumdraw-bar pull, said spring resistance unit having an additional capacityavailable in co-opcration with the friction unit during the actuationolthe latter in absorbing shocks in excess of the said available freespring capacity of the spring resistance unit.

:5. In a combined spring anl friction shock absorbing mechanism adaptedfor draft riggings of standard passenger equip ment subject to asustained tractive force approximating the sustained maximum tractiveeffort of the locomotive -of said standard equipluent, the. combinationwith a friction system having movement as a unit to a limited extent,said system including cooperating friction nu-mbers having relativemovement after the movement of said friction system as a unit islimited; of a cushioning spring means successively reisting movement ofsaid friction system as a unit and relative movement: of said members.whereby compression of said spring is effected in two successive stages,the capacity of resistance of said spring during the first stage beingat; least as great as the sustained maximum tractive effort applied tothe gear in standard passenger practice.

3. In a combined spring aiul friction shock absorbing mechanism adaptedfor railwa draft riggings subject to-a tractive force approximating themaximum tractive effort of a standard passenger locomotive. thecombination with a friction system incb din; cooperating relativelymovable friction el ments: of a spring cage, said cage and one of =aidelements having limited .relative 'movement; wedge pressure trans-:Initting means for forcing said elements into intimate frictionalcontact; a cushioning spring element within the spring cage adapted toresist movement of-said friction .system. the elements of said frictionsystem -being bodily. movable as a unit until said element having thelimited movement is arrested to transmit the actuating force directly tothe cushioning spring, thereby compressing the latter to-a predeterminedextent, said friction elements being forced to 7 move relatively to eachother upon said eleing said predetermined amount o ment having limitedmovement being arrested. and further compression of the mechanism,effecting still further compres sion of the spring to absorb -abnormalshocks, the total capacity of said 5 ring durf compression being atleast as great as the sustained maximum tractive effort a plied to thegear in standard passenger prac ice.-

4."In a shock absorbing mechanism adapted forrailway draft riggingssubjectto a tractive force approximating the maximum tractive effort ofa standard passenger locomotive, the combination with a spring casing;of a friction member having limited movement with respect to (thecasing. the extent of movement approximating half of he compressionstroke of the mechanism; iriction elements cooperable with said memoer;spring means disposed within the casing and resisting relative movementof said Y member and casing and further resisting relative movement ofsaid friction elements and member aft-er relative movement of the casingand member is limited. the total capacity of said spring during saidlimited movement of the friction member being at leastas great as thesustained maximum tractive effort applied to the gear in standardpassenger practice.

5. In a shock absorbing,mcchanisim. the

' combination with a spring c'age; of a friction shell. said shell andcage having limited relative movement; friction elements cooperatingwith said shell and having movement relative thereto; means foreffecting movement of said friction elements and forcing the same intointimate contact with the shell; and a main spring resistance opposingrelative movement of the shell and cage and op- Losing relative movementof the friction elei ents and shell successively, said main springresistance being of at least 75,000

pounds capacity.

6. In a shock absorbing mechanism adapted for railway draft riggingssubject to a tractive force approximating the maximum tractive effort ofa standard passenger locomotive, the combination with a spring cage; ofa friction shell, said shell and cage having limited relative movementof at least one inch; friction means cooperating with the shell andhaving movement relative thereto,

said friction means including lateral pressure creating means and amainspring resistance opposing relative movement of said shell and cage andrelative movement of said friction elements and shell successively, thetotal capacity of said main spring resistance at one inch of compressionbeing at least as great as the sustained maximum tractive efl'ortapplied to the gear in standard passenger practice and exceeding 30,000pounds.

7. In a shock absorbing mechanism adapted for railway draft'riggingssubject to a tractive force approximating the maximum tractive effort ofa standard passenger locomotive. the combination with a column element;of friction means including a friction member and cooperating frictionele-' ments. said member and column element having relative movement toa predetermined extent; a spring resisting relative movement of saidcolumn element and memher to provide free spring action and alsoresisting relative movement of said member and friction elements toprovide ultimate highcapacity,- the. free spring resistance of the.mechanism being in excess of the maximum sustained tractive effort ofastandard spring resistance within the .cage; and a spring followerinterposed between the shell and spring. said follower and shell havinginterengaging lugs to prevent relative lateral displacement of the shelland follower.

9. In a friction shock absorbing mechanism. the combination with acasing open at one end thereof; of. a friction shell disposed at saidopen end of the'casing; cooperating shoulders on the shell and easingadapting the shell for a limited amount of movement with respect to thecasing; friction elements cooperating with the shell; spring means disposedwithin the casing; a follower c00perating with the spring meansadjacent the end of the shell. said follower having abutment meansthereon engaging the end of the shell; and means on the shellcooperating with the follower'abutment means for preventing accidentaldisengagement of said shell and casforce equal to said tractive force, anormal compression stroke less than the full compression stroke of thesame, the combination with a spring cage and a friction system, saidsystem including a plurality of movable elements, said elementscomposing said friction system, being bodily movable in-unison withrespect to the spring cage to a limited extent equal to the normalcompression stroke of the mechanism; of means for limiting movement ofone of said elements of the friction system after the mechanism has beencompressed to said limited extent,- whereby said friction elementsarecompelled to move relatively upon further compression of themechanism beyond said normal compression stroke; and a springresistanreopposing bodily movement of saidfriction system and relativemovement of the elements thereof. the capacity of said spring resistancewhile opposing relative movement of said friction system and cage tosaid limitedextent being such as to absorb all normal shocks to whichthe gear is subjected, whereby the remaining capacity of said spring isavailable to oppose relative movement of said friction elements toabsorb abnormally heavy shocks.

11. In a friction shock absorbing mecha nism adapted for railway draftriggings, subject to a tractive force approximating the maximum tractiveeffort of a standard pas-' senger locomotive and having, when subjectedto a force equal to said tractive force, a normal compression strokeless than-the full compression stroke of the same, the combination witha spring cage; ofa friction shell, said shell and cage bein relativelymovable to an extent less than t e full and equal to the normalcompression stroke of the mechanism; a friction system cooperating withthe shell, said system and shell being relal ively movable during theremainder of the compression stroke to absorb excessively heavy abnormalshocks; and 5 ring means opposing relative movement 0 said shell andcage to the extent of said normal stroke. and opposing. relativemovement'of the friction'system a'ndshell when said gear is compressedto an extent exceeding said normal stroke.

12. In a friction shock absorbing mechanism, the combination with. aspring cage; of a friction shell. said shell and cage having limitedrelative movement; a. spring resist ance within said cage; springfollower means interposed between the shell and spring resistance, saidspring follower means bearing on the inner end of the shell; a frictionwedge system cooperating with the Shell; and. auxiliarvspring resistancemeans interposed between said system and spring follower means.

13. In a friction shock absorbing mechanism. the combination: with apressure transmitting member; of a spring rage, said member and cagebeing relatively movable; a friction shell, said shell and cage havinglimited relative movement; friction shoes co operating with the shell; awedge co-operatspring cage, and also opposing relative movement of saidshell and shoes after a predetermined relative movement of said shelland shoes; and anauxiliary spring resistazice opposing relative movementofsaid shell and shoes independently of the main spring resistance.

14. In a friction shock absorbin nism the combination with a. frictionshell provided with friction surfaces; of friction shoes cooperatingwith the shell, said shoes bein relatively movable to the shell; meansfor forcing saidshoes against said shell surfaces and inwardly of. themechanism; a spring cage, said shell and cage having relativemovement-to a limited extent; a main spring resistance withinlihe cage;an auxiliary spring resistance opposing relative movement of said shoesand shell; means including a spring follower'for limiting the relativemovement of said shoes and shell opposed by said auxiliary springresistance and thereafter transferring the actuating force from saidshoes directly to the main spring resistance, said spring follower alsodirectly transmitting the actuating force from the shell to the mainspring resistance during relative movement of said-shell and ca e.

I5. In a friction shock absorbing mecha nism, the combination with afriction mem-- ber; of a spring supporting column element, said memberand element having limited relative movement a main spring resistancesupported by said element, said spring resistance opposing relativemovement of the member and element to provide for free spring action ofthe mechanism; movable friction means co-operating with said member,relative movement of said means and member-being opposed by said mainspring to provide heavy frictional resistance subsequently to said freespring action; and an auxiliary spring resistance opposing relativemovement of said member and means independently-of said main springresistance to provide for a transition period of light frictionalresistance.

16. In a friction shock absorbing mechanism, the combination with a.friction member provided with friction surfaces; of friction shoesco-operatingwith the friction surfaces of said member, said shoes beingrelatively movable to said member; means for mechaforcing said shoesagainst the surfaces of c spring resistance opposing relative movementof said shoes and member; means including a spring follower for limitingthe relatie movement of sa icf shoes gmd memhm'c' during relativemovement of said memberopposed by said auxliaary spring resie'tandelement. ance and thereafter transferring the actuat- In witness that. Ichum the [(NErroinw I In I Lug-force from said shoes directly to the mamhave hereunto subscribed my name tTlIS 3156 spring resistance, saidspring follower also day of October 1925.

directly transmitting the actuating force from said member to the mainspring resist- ALBERT P. WITHALL.

